TITLE:   GCN CIRCULAR
NUMBER:  26053
SUBJECT: GRB 191019A: Swift/UVOT Detection
DATE:    19/10/21 22:05:22 GMT
FROM:    Sam LaPorte at PSU  <sjl5346@psu.edu>

GRB 191019A: Swift/UVOT Detection

S. J. LaPorte (PSU) and K. K. Simpson (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 191019A
3294 s after the BAT trigger (Simpson et al., GCN Circ. 26031).
A fading source consistent with the XRT position
(Evans et al. GCN Circ. 26034)
is detected in the initial UVOT exposures.

Preliminary detections and 3-sigma upper limits using the UVOT photometric
system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures
are:

Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

b               4541          4741             196
19.55+-0.30
uvm2        5361          5561             196              >19.20
u               4336          4536             196              >19.43
v               5156          5356              196             >18.75
uvw1        4131          4331              196              >19.13
uvw2        4952          5151              196              >19.28
white        4746          4946              196                19.66+-0.20

white      27982        28668              668                20.27+-0.18

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.04 in the direction of the burst
(Schlegel et al. 1998). Additionally, these magnitudes likely include a
contribution
from the probable host-galaxy, as reported by TSHAO (Reva et al., GCN Circ.
26036),
NOT (Fynbo et al., GCN Circ. 26041), and GROND (Guelbenzu et al. GCN Circ.
26042).